Two Eyes


The hole in ths white group is called an eye.

When a group has only one eye, like this, you can capture it. Do you remember how?

Right now, this would be suicide. White still has 2 liberties on the outside.

But after Black has played on all the outside liberties, White has only one liberty left, and then ...

... Black can now play here and capture the white stones!

Black ends up getting 8 prisoners and 8 points of territory - worth 16 points altogether!

This time the white group has two eyes. Let's see if we can capture it now.

First, let's fill all the outside liberties, as before.

Next, Black can't play here, because it's suicide. White still has a liberty in the other eye.

And Black can't play here either. It's just the same!



A group with two eyes can never be captured!


Does this white group have two eyes, or can Black capture it?

Black can start here. He still has a liberty.

Next, if White plays somewhere else, Black can play the other liberty and capture all the white stones.

White can capture the black stone, but is there any point?

After White takes off the stone he captured, it's like this. The white stones have only one liberty. Black can capture them any time he needs to.



To have two eyes, you need a nose between them!



Challenge! Dead or alive?

Decide whether each black group is dead or alive.

(Stones are alive if they can't possibly be captured, and dead if they can't ever avoid being captured.)



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snapbacks table of contents unsettled groups & vital points

UK Go Challenge home 1 November 2003